Spectrum Computing

A bit of programming, but since it's graphic oriented, I'm posting it here.

With the help of my old TC2048 manual, I had a little fun working with the Timex 512x192 mode from Basic.
Nothing extraordinary, just trying to write to screen sequentially
Of course, poking 127 will only get a line pattern on screen. A more advanced example would read an image for some other memory position.


Another interesting note is the list of colours available for the Highres mode.
OUT 255,6 = black,white
OUT 255,14 = blue,yellow
OUT 255,22 =red,cyan
OUT 255,30 = magenta,green
OUT 255,38 = green, magenta
OUT 255,46 = cyan,red
OUT 255,54 = yellow,blue
OUT 255,62 = white,black


I wonder if it would be possible to do "multicolour" or simulate attributes in some way by changing the mode in machine code?
The combinations are not that great but with a well prepared image, it may look good...
I'd really like to know if this is possible!

It probably works! However it would result in a very restricted multicolor 24x.5 (perhaps even wider depending on Timex port contention, I didn't check), limited to the few color combinations that you mentioned.

This is not a convenient format for producing interesting graphics... Although now that I said it, someone will probably try to draw something just to prove me wrong! :)

Einar Saukas wrote: ↑Fri Nov 17, 2017 2:55 pm very restricted multicolor 24x.5

Can you make that clearer ? Is that 24 pixels by 1/2 pixel ?
I know very little of machine code, but I understand this is related to timings (screen writing vs port value update).

4thRock wrote: ↑Fri Nov 17, 2017 3:41 pmCan you make that clearer ? Is that 24 pixels by 1/2 pixel ?

Exactly.

Each multicolor "cell" would be 24 (at least) pixels wide, half pixel high. Each multicolor cell could have 1 pair of colors, out of 4 combinations.

4thRock wrote: ↑Fri Nov 17, 2017 3:41 pmI know very little of machine code, but I understand this is related to timings (screen writing vs port value update).

It takes at least 12 T-states to execute a port access instruction to switch colors. In 12 T-states, the raster beam will render 24 pixels in a horizontal line. Therefore you can only choose another pair of colors every 24 pixels.

(Assuming these Timex ports are not contended, otherwise it should take more than 24 pixels.)

BTW these multicolor "cells" don't need to be aligned vertically. They can start at a different column on each pixel line. Perhaps it could help generate more interesting images this way.

For the sake of discussion, I tried to mock-up an image, simply alternating black/white and blue/yellow on each line.


It's not a bad colour scheme...

It has been often discussed that Times HiColor for upper part of the screen + Timex HiRes for lower part of the screen makes a great layout for text adventures.

Handle than from basic It's not easy though, but it's definitively possible in assembler.

Was that a screenshot from "Space 1999" ?

Yes, that's Maya

Here's another attempt now using Black+White + Red+Cyan.



Sorry for the mediocre conversion, she deserves much better !